The present invention relates to apparatus and methods for downhauling a sail. More particularly, the invention relates to apparatus and methods for downhauling a sail which is movably attached to a mast assembly and is coupled to a downhaul line adapted to be held at varying points along its length by a gripping means which is part of the mast assembly.
A sail board or wind surfing craft generally has a single sail. This sail must be placed under tension before use. The sail is generally placed under a high degree of tension to prevent the sail from being deformed by its motion through the air and to facilitate use at high speeds.
Ordinarily, the sail is attached to a mast and then, using a mast base, the sail and mast are attached to the board. The sail often has a sleeve at the leading edge. The sail is movably attached to the mast, for example, by sliding the sleeve over the mast from the top of the mast. A cap at the top of the sleeve eventually limits travel of the sleeve down the mast. An elongated downhaul line is coupled to the sail. A free end of the elongated line is passed through a gripping assembly, often a cleat, attached to the mast base, which is secured to the mast. The gripping assembly allows tension to be applied to the sail by pulling on or downhauling the portion or segment of the downhaul line extending through the gripping assembly. The gripping assembly maintains the tension by preventing the downhaul line from returning through the gripping assembly. Once the sail is tensioned, the mast assembly is attached by the mast base to a mast cup mounted on the board or craft and the assembly is complete.
A substantial amount of force is required to properly tension the sail. If this tensioning was to be done without any mechanical assist, injuries (for example, lower back injuries) and abrasions might result.
Purdy U.S. Pat. No. 5,239,939 discloses a device for downhauling such a sail. However, the disclosed device involves an additional cleat to provide for ratchetting action. This relatively high degree of mechanical complexity increases the cost and maintenance requirements of the system and reduces system reliability. In addition, the fulcrum of the lever used in the Purdy system is located near the center of the lever arm, disadvantageously reducing the mechanical advantage obtained in using such a system.